1. Field of the Invention
The present invention relates to an apparatus and a method for monitoring the state of a battery, in which a micro-processor is used to accurately measure the current state of a battery used for supplying electric power in electric automobiles and the like.
2. Description of the Prior Art
A conventional system for measuring the residual capacity of batteries is disclosed in U.S. Patent 4,823,086, and, in this invention, wires are used for measuring the charge state of individual batteries. However, in this case, the wiring is complicated, and therefore, the maintenance and replacement become a difficult problem.
Further, in this method, the residual capacity is computed by measuring the voltages and currents of the opposite terminals, regardless of the charge/discharge state of the batteries. Therefore, the computed result does not show the exact residual capacity. Further, the overall charge/discharge state is measured, and therefore, the charge/discharge state of the individual batteries cannot be known. Therefore, an inefficient charging may be carried out, or over-charging may be carried out for a part of the batteries. PA1 Further, during the operation of the system, defective or malfunctioning batteries cannot be known. PA1 a plurality of passive modules including: an A/D converter for converting analog signals of the voltages, currents and temperatures of a plurality of batteries into digital signals within certain time intervals; a micro-processor for computing the charge state of the batteries based on the output of the A/D converter and a plurality of displays for displaying the battery charge state computed by the micro-processor; PA1 an active module including: a micro-processor for computing the overall residual capacity of the batteries by obtaining information from the individual passive modules a storing means for storing the above information an auxiliary memory means for storing the information during the system-off a display for displaying the residual capacity of the plurality of the batteries; and PA1 two serial lines for connecting the passive modules and the active module. PA1 the method including: